JPH0667509A - Discharge device - Google Patents

Abstract

PURPOSE:To eliminate ozone and to prevent deterioration of a photosensitive body due to ozone at a low cost with a simple construction provided in an exhaust pipe. CONSTITUTION:The exhaust pipe 8 is provided on the downstream side of the rotation of the photosensitive drum 6 of the discharge device 7, the space h2 between bottom edges of side walls 17b and 18a in a part connected with the exhaust pipe 8 of a shield plate 17 of the discharge device 7 and the photosensitive body 6 is made wider than the space h1 between the bottom edge 17a of a side wall upstream side of the shield plate 17 of the discharge device 7 and the photosensitive drum 6 and the space h3 between the bottom edge of a side wall 18b downstream side of the exhaust pipe 8 and the photosensitive drum 6 and an ozone filter 9 which is an ozone elimination means is provided in the exhaust pipe 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharging device for charging and discharging an image forming apparatus such as an electrophotographic copying machine or an electrostatic recording device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrostatic recording device or an electrophotographic copying machine, charging of a photoreceptor of an image carrier, transfer of a toner image to a transfer material, separation of the transfer material from the photoreceptor. The corona discharge method in which a discharge electrode is composed of a thin metal wire having a wire diameter of about 0.1 mm and a corona discharge is generated by applying a high voltage to the discharge electrode is used for charging and discharging for the purpose. However, in such a corona discharge method, ozone is generated, which not only harms the health of the operator, but also causes ozone to accumulate in the apparatus and deteriorate the photoconductor of the image bearing member to cause bleeding in the image, which is not significant. May be blurred. In addition, even if the discharge electrode is slightly soiled, there is a drawback that uneven discharge occurs, and the body to be charged (charge removal) is unevenly charged (charge removal), and the uneven discharge shortens the life of the corona discharger. There was a flaw.

Therefore, conventionally, as shown in JP-A-48-41750, JP-A-58-111054, and JP-A-58-182659, a fan is installed at an appropriate position of an image forming apparatus. , A method of forcibly blowing air from the outside to the discharge electrode surrounded by the shield member to discharge ozone and prevent foreign matter such as toner from adhering to the discharge electrode,
As shown in JP-B-51-10785, a method has been proposed in which an ion wind outlet is provided in a part of the shield member and ozone or the like generated by corona discharge is exhausted from this outlet. .

[0004]

However, in the above method, it is necessary to provide a fan or the like in the apparatus, which cannot prevent an increase in cost, and also has a disadvantage of hindering miniaturization. In addition, the method of providing the shield member with the discharge port for allowing ozone to escape to the corona discharger without providing a fan or the like cannot obtain a sufficient effect on the deterioration of the photoconductor.

An object of the present invention is to solve the above problems and to provide an electric discharge device which removes ozone with a simple structure and prevents deterioration of a photoreceptor due to ozone at low cost.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a discharge device having a discharge electrode surrounded by at least two sides of a shield member, wherein an exhaust tube is provided on the downstream side of the rotation of the image carrier of the discharge device. The discharge device is characterized in that ozone removing means is provided in the exhaust stack.

Further, the gap between the image carrier and the lower end of the side wall of the portion of the shield member of the discharge device that is connected to the exhaust tube is defined by the lower end of the side wall of the shield member of the discharge device and the image carrier. And the gap between the image carrier and the lower end of the side wall on the downstream side of the exhaust pipe, which is a preferred embodiment.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is an overall configuration diagram showing an example of an image forming apparatus equipped with the discharge device of the present invention. The schematic configuration and function of the image forming apparatus will be described with reference to FIG.

The image forming apparatus shown in FIG. 3 comprises an optical scanning section A provided on the upper portion of the main body and an image recording section B provided on the lower portion thereof. A document table 1 made of a transparent glass plate and a document cover 2 for covering a document D placed on the document table 1 are arranged above the optical scanning unit A. Below the platen 1,
The optical scanning unit A has an exposure lamp 3a and a first mirror M1.
A first mirror unit 3 provided with is mounted parallel to the document table 1 and linearly movable in the left-right direction in the drawing, and optically scans the entire surface of the document D. M2 and M3 are a second mirror and a third mirror, respectively, and the second mirror unit 4 in which these are integrated is left / right at a speed half that of the first mirror unit 3 so as to maintain a predetermined optical path length. Move straight to. Of course, the movement of the second mirror unit 4 is parallel to the document table 1 as in the case of the first mirror unit 3. The image of the document D on the document table 1 is the first
An image is formed on the photosensitive drum 6 as an image carrier through the mirror M1, the second mirror M2, the third mirror M3, the main lens 5 and the fourth mirror M4. When the scanning is completed, the first mirror unit 3 and the second mirror unit 4 return to their original positions and stand by until the next image recording.

In the image recording section B, the photosensitive drum 6
Is rotated in the clockwise direction as shown by the arrow at the start of recording and is charged by the charger 7 which is a discharge device including a corona discharger. An electrostatic latent image corresponding to the document D is formed on the photosensitive drum 6. After that, the photoconductor drum 6
The electrostatic original latent image above is developed by the developing device 10 to become a visible toner image.

Paper feed cassette for storing a large number of recording papers P
The recording paper P is fed from 20 by the first paper feed roller 22 one by one. The fed recording paper P is conveyed by the conveying roller 21 to the second paper feeding roller 23, and is transferred onto the photosensitive drum 6 by the second paper feeding roller 23 which operates in synchronization with the toner image on the photosensitive drum 6. Sent out.

Thereafter, the toner image on the photosensitive drum 6 is transferred onto the recording paper P by the action of the transfer device 12 which is a corona discharger. After being separated from the photoconductor drum 6 by the separator 13 and the separation claw 13a, which are also corona dischargers, the recording paper P passes through the recording paper conveying means and the fixing device 25
Then, after being melted and fixed by the heat fixing roller and the pressure bonding roller, the sheet is discharged by the discharge roller 26 to the outside of the apparatus.
On the other hand, the surface of the photoconductor drum 6 is scraped off and cleaned by the cleaning device 14 equipped with a blade 14a and the like, and the toner remaining on the drum without being completely transferred is awaited for the next image recording. Reference numeral 28 denotes a fan that discharges the air inside the device and prevents the temperature inside the device from rising.

In the above-mentioned image forming apparatus, an example in which the present invention is applied to the charging device 7 which is a discharging device for generating a large amount of ozone is shown.

FIG. 1 is a cross-sectional view perpendicular to the longitudinal direction of an embodiment of the discharge device of the present invention. In the figure, 7a is a discharge electrode made of, for example, a tungsten wire having a wire diameter of 0.06 mm, 7b is a control grid made of, for example, a tungsten wire provided so as to perform stable charging, 17 is a shield plate as a shield member, and 17a is An upstream side wall of the shield plate 17 (seen from the rotation of the photoconductor drum 6), 17b also a downstream side wall of the shield plate 17, 8 an exhaust pipe provided downstream of the discharge device 7, and 18a an exhaust pipe. Reference numeral 8 denotes a side wall of a portion of the discharge device 7 which is connected to the side wall 17b, 18b denotes a downstream side wall of the exhaust stack 8, and 9 denotes an ozone filter which is an ozone removing means provided in the exhaust stack 8.

The gaps h1, h2, h3 between the lower ends of the side walls 17a, 17b, 18a, 18b and the photosensitive drum 6 are, for example, h1 = h3 =
1 mm and h2 = 4 mm, and the gap h2 is set larger than the gaps h1 and h3.

The shield plate 17 is grounded, and a predetermined high voltage DC voltage is applied to the discharge electrode 7a from a high voltage power source (not shown). A DC voltage lower than the high DC voltage and slightly higher than the desired charging voltage of the photoconductor drum 6 is applied to the control grid 7b. Therefore, a strong ionic wind blows from the discharge electrode 7a toward the photoconductor drum 6, and the ionic wind flows to the downstream side by the rotation of the photoconductor drum 6, but the shield plate 17 and the side walls 17a, 17 of the exhaust pipe 8 are provided.
Since the gaps between b, 18a, 18b and the photoconductor drum 6 are configured as described above, the resistance of the passages at the lower ends of the side walls 17a and 18b is large and the ion wind flows into the exhaust pipe 8 as shown by the arrow in FIG. As a result, harmful ozone is removed when passing through the ozone filter 9.

FIG. 2 is a sectional view showing another embodiment of the discharge device of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. This embodiment is different from the embodiment shown in FIG. 1 in that an intake port 19 is formed in the upper part of the shield plate 17. By providing the intake port 19, the ionic wind becomes stronger, and the ionic wind passes through the exhaust pipe 8 more completely, so that the ozone removing effect is increased.

[0019]

According to the present invention, the exhaust pipe is provided on the downstream side of the discharge device, the shield member and the side wall of the exhaust pipe are constructed as described above, and the ozone filter as the ozone removing means is provided in the exhaust pipe. Since it is provided, ozone is removed with a simple configuration without providing a fan for ozone discharge, and it is possible to prevent the deterioration of the photoreceptor and the occurrence of image unevenness due to ozone at low cost, and to improve the health of the operator of the image forming apparatus. It has become possible to provide a discharge device that obtains good image quality without harming.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a discharge device of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the discharge device of the present invention.

FIG. 3 is an overall configuration diagram showing an example of an image forming apparatus including a discharge device of the present invention.

[Explanation of symbols]

 6 Photoreceptor Drum (Image Carrier) 7 Charging Device (Discharging Device) 8 Exhaust Cylinder 9 Ozone Filter (Ozone Removing Means) 10 Developing Device 12 Transfer Device 13 Separator 17 Shield Plate (Shield Member) 19 Air Intake Port A Optical Scanning Section B Image recording section

Claims (2)

[Claims] 1. A discharge device having a discharge electrode surrounded by at least two sides in at least a shield member, wherein an exhaust tube is provided on a downstream side of rotation of an image carrier of the discharge device,
A discharge device, wherein ozone removing means is provided in the exhaust stack. 2. The gap between the lower end of the side wall of the shield member of the discharge device that is connected to the exhaust pipe and the image carrier is defined by the lower end of the side wall on the upstream side of the shield member of the discharge device and the image carrier. 2. The discharge device according to claim 1, wherein the gap is larger than the gap between the image carrier and the lower end of the side wall on the downstream side of the exhaust tube.